This invention relates to cleats for use with shoes worn on turf, and particularly to a golf cleat that provides enhanced traction without adversely affecting the turf, and at the same time is resistant to wear when worn on other surfaces.
The need for improved traction on turf surfaces is well known. Specialized shoes for many different sports--e.g., baseball, football, soccer and golf, among others--have structure provided on their soles to enhance traction. Taking golf as a representative example throughout the remainder of this specification, it has long been known to provide golf shoes with relatively large metal spikes for traction.
For almost as long as they have been in use, golf spikes (and similar structures provided on athletic shoes for other turf sports) have also been known to adversely affect the turf of golf courses (or other playing surfaces), and particularly putting greens. The large spikes tear into the putting green surface, particularly when a golfer drags his or her feet as many do, leaving "spike marks" that disrupt the carefully manicured surface and adversely affect the trajectories of putted golf balls. So well known are spike marks in golf that the rules of the game have been adapted to account for their presence (the rules prohibit repairing spike marks before putting). In addition to affecting players' putting, spike marks also affect groundskeepers, who after a day of play by numerous spike-wearing golfers have to spend hours repairing the various putting greens on their golf courses.
In addition to the annoyance to players and groundskeepers caused by the marks that they leave, traditional golf shoe spikes also affect the health of grass all over the golf course, not only on greens. First, the spikes penetrate a significant distance into the ground, frequently damaging a portion of the grass plant above the roots, known as the "crown." Damage to the crown often kills the plant. Second, the spikes pick up seeds of undesirable plants--including weeds and grasses (e.g., Poa annua)--and inoculate those seeds into the greens, causing growth of undesirable plants.
Traditional metal golf spikes are also damaging to the floor surfaces of golf clubhouses, and may actually exacerbate slipping on certain clubhouse floor surfaces such as marble. Traditional metal golf spikes even cause damage to paved outdoor walkways.
One known solution to the problems caused by traditional golf spikes is shown in commonly-assigned U.S. Pat. Nos. 5,259,129 and 5,367,793, which are hereby incorporated by reference in their entirety. Those patents show a golf cleat that attaches to the same golf shoe fittings designed for traditional spikes. The cleat is preferably made from a plastic material having a preferably convex lower surface bearing a plurality of ribs that distribute the golfer's weight to produce a plurality of gripping forces--which are mainly frictional--in a plurality of directions, without puncturing the turf, thereby reducing the adverse affects described above.
Cleats such as those described in the aforementioned patents recently have become increasingly popular. Other nonmetallic alternatives to metal spikes, having different types of ribs or protrusions, have also come into use.
One drawback of nonmetallic spike alternatives has been that, because the cleats are worn not only on the turf portions of the golf course, but also on paved walkways and other hard surfaces, the ribs or protrusions that provide the traction on turf are gradually abraded away by the hard surfaces, much faster than they would be if worn exclusively while walking on turf. As a result, the ability of the cleat to provide traction is reduced or destroyed, and the cleat must be replaced sooner than if it were worn exclusively on turf.
One solution to this wear problem is shown in copending, commonly-assigned U.S. patent application Ser. No. 08/823,901, filed Mar. 25, 1997. The cleat shown there has a flange with an attachment stud for attaching to a receptacle in a shoe sole, a plurality of traction protrusions on the flange to engage grass blades to provide traction without damaging turf, and a bearing portion that bears the wearer's weight, particularly when the wearer walks on a hard surface. In the preferred embodiment shown, the bearing portion is a dome-shaped central portion. The protrusions are thereby less affected by the abrading effects of the hard surface, and last longer before they are worn to the point that they must be replaced.
In all of the foregoing cleats, however, if one of the traction elements encounters a hard surface, it will be abraded. It would be desirable to be able to provide an athletic shoe cleat having traction elements whose abrasion when worn on hard surfaces is minimized.
It would also be desirable to provide such a cleat having enhanced traction.